Hi
I am knitting my first sweater. I came to this part and am unclear how to proceed. After I have "shaped the neck" it then says to :
Change to seed st (get that) and working each side separately, dec 1 st at neck edge every other row 4 times. Slip remaining sts to holder.
Help!~

It just means, I think, work the left side to the shoulder seam and then work the right side to the shoulder seam, instead of doing one row on the left and one on the right leaving a long string of yarn between the two sides.

To work both sides separately, you'll need two balls of yarn. The left side of of V will use one ball and the right the other. You can either complete the left side, then complete the right. Or you can alternate by knitting one row on the left side and then knit one row of the right and continue working left, then right. When it says to dec at neck edge, the just means to work a dec st on the edge of the work that will touch the neck. If you're wearing the item, you would dec on the right edge of the left side and the left edge of the right side.